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Open top container bodies or receptacles such as those used on dump trucks and roll-off trash dumpsters often hold loads that are easily agitated by forces from bumpy roads, external winds, and the air stream created by vehicular movement. Accordingly, a flexible cover is often secured on top of these container bodies to shield the contents. Container bodies are often up to forty feet long and as wide as the vehicle upon which they are carried, and the covers for such large bodies are themselves large and unwieldy. Some form of mechanical assistance is thus often used to furl and unfurl the covers over the bodies.
Prior art truck covering systems typically provide a flexible cover that is attached at one end to a crossbar that extends transversely across the open top of a container body. The other end of the cover is attached to a roller, which is mounted to a cab shield at the front edge of the container body. A pair of pivoting arms connected to the crossbar is mounted on the sides of the container body and is actuated by hydraulic or pneumatic cylinders, also mounted on the sides of the container body. Pivoting actuation of the arms causes the cover to be drawn from the roller over the open top of the container body.
Because the arms and cylinders are mounted on the sides of the container body, they are vulnerable to being hit during loading operations. Also, some mechanism to keep the arms in synchronization during movement is preferably provided to minimize wear on the covers.
A truck cover system having a hold down tensioning device is also known. In this system, spring biased arms attached to a tensioning bar urge the cover toward the top edge of the container body, keeping the tensioned cover close to the top edge of the sides of the body. See U.S. Pat. No. 5,957,523, the disclosure of which is incorporated by reference herein.
In the present invention, a covering system is provided having pivot arms connected to a common shaft that runs from side to side underneath the container body and that ensures the arms move in synchronization. The pivot arms are connected to the shaft at the outboard ends. The shaft is rotated by a mechanism that converts linear motion to rotary motion, such as a hydraulically or pneumatically operated bell crank. This mechanism is connected to the center of the shaft underneath the truck body, thereby keeping the mechanism out of harm""s way and transmitting equal amounts of torque to the pivot arms, which in turn deploy the cover or tarp over the load. The covering system may be run with compressed air from the truck""s air supply or hydraulic fluid provided by the truck""s hydraulic system if the truck is equipped with a central hydraulic system that is used to run other functions, such as sanders and plows.
In a further embodiment, a tensioning device is provided comprising a hoop rotatably mounted to a front of the container body to travel an arcuate path between an uncovered position near a top of the roller mechanism and a covered position holding down the cover close to a top of the container body. The tensioning device may be actuated by the hydraulic or pneumatic circuit provided for actuating the covering system, or may be a standalone system.